//
// Copyright (C) 2014 The Android Open Source Project
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//

#ifndef TRUNKS_COMMAND_TRANSCEIVER_H_
#define TRUNKS_COMMAND_TRANSCEIVER_H_

#include <string>

#include <base/callback_forward.h>
#include <trunks/tpm_constants.h>

namespace trunks {

// CommandTransceiver is an interface that sends commands to a TPM device and
// receives responses. It can operate synchronously or asynchronously.
class CommandTransceiver {
 public:
  typedef base::Callback<void(const std::string& response)> ResponseCallback;

  virtual ~CommandTransceiver() {}

  // Sends a TPM |command| asynchronously. When a |response| is received,
  // |callback| will be called with the |response| data from the TPM. If a
  // transmission error occurs |callback| will be called with a well-formed
  // error |response|.
  virtual void SendCommand(const std::string& command,
                           const ResponseCallback& callback) = 0;

  // Sends a TPM |command| synchronously (i.e. waits for a response) and returns
  // the response. If a transmission error occurs the response will be populated
  // with a well-formed error response.
  virtual std::string SendCommandAndWait(const std::string& command) = 0;

  // Initializes the actual interface, replaced by the derived classes, where
  // needed.
  virtual bool Init() { return true; }
};

}  // namespace trunks

#endif  // TRUNKS_COMMAND_TRANSCEIVER_H_